Table of Content

12 April 2026, Volume 52 Issue 4

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REVIEW

Research progress in biosynthesis and action mechanism of sRNAs and their regulation on seed development, dormancy and germination

Song Song-Quan, Tang Cui-Fang, Liang Yu-Rong, Cheng Hong-Yan, Wang Wei-Qing

Acta Agronomica Sinica. 2026, 52(4):  959-981.  doi:10.3724/SP.J.1006.2026.53074

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The development, dormancy and germination of seeds are critical processes in the plant life cycle, and are regulated by various genetic factors and environmental cues. Small RNAs (sRNAs) are a group of non-coding RNA molecules consisting of 19-24 nucleotides, and regulate the expression of genes encoding transcription factors and key regulatory proteins. They play important roles in morphogenesis, growth, development, and response on biotic and abiotic stresses in both plants and animals. Although some of the regulation mechanisms of plant sRNAs remain unclear, existed evidences indicate their significant regulatory roles in seed development, dormancy, and germination. In the present paper, the research progresses of plant sRNAs in recent years were reviewed, mainly including sRNA biogenesis (biosynthesis) and action mechanism, as well as their regulatory roles in seed development, dormancy, and germination. Additionally, we have highlighted key scientific issues requiring further investigation in this field. The aim is to deepen our understanding of sRNA-mediated molecular mechanisms in these processes, thereby providing insights into improving seed quality, yield, and germination vigor.

Physiological basis and practical strategies for enhancing rapeseed yield under direct seeding

Kuai Jie, Lou Hong-Xiang, Tan Xiao-Qiang, Gao Geng-Dong, Shao Dong-Li, Xiao Sheng-Nan, Zhao Jie, Xu Zheng-Hua, Wang Jing, Wang Bo, Zhou Guang-Sheng

Acta Agronomica Sinica. 2026, 52(4):  982-992.  doi:10.3724/SP.J.1006.2026.55070

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Enhancing the self-sufficiency rate of edible vegetable oil and ensuring the security of oil supply represent a critical challenge for oilseed production in China. Rapeseed is a vital source of both edible oil and feed protein. Since 2000, China’s rapeseed production system has progressively transitioned from seedling transplantation to a modernized model centered on direct-seeding cultivation. Within this systematic technological evolution, a foundational framework for direct-seeding rapeseed production has been largely established. The adoption of rational close planting has not only effectively reduced production costs and enhanced efficiency but has also provided key technological support for safeguarding domestic edible oil supply and promoting sustainable agricultural development. However, this new model still faces a series of scientific and technical problems requiring urgent resolution. A core research question, particularly under high-density planting conditions, is how to synergistically increase yield per unit area and resource use efficiency. Research focus is gradually shifting from constructing macro-level cultivation systems to a deeper analysis of the key agronomic factor-“close planting”-aiming to elucidate the underlying theoretical mechanisms and practical constraints for yield and efficiency gains, thereby guiding future technological breakthroughs. This paper summarizes the development status of direct-seeding rapeseed in China and proposes a developmental stages framework (Stage 1.0 to 4.0). It analyzes the limiting factors for achieving high yield and efficiency under close planting, which manifest as non-synergistic yield components, weak individual plant growth, and severe lodging. Drawing insights from ideal plant architecture research in cereal crops, the paper discusses traditional and smart ideal plant architecture traits for lodging-tolerant and high-yielding direct-seeding rapeseed, along with their physiological basis, focusing on efficient biomass accumulation and partitioning, improvement of stem strength and lodging resistance, and root-shoot synergy to enhance density tolerance. Pathways for yield improvement and future research directions are further clarified. With ongoing advances in functional gene discovery and technology commercialization, the rapeseed production system is poised to evolve further towards high yield, high efficiency, and intelligentization.

CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

A novel set of tri-allelic variant SNP loci suitable for maize variety identification

Tian Hong-Li, Yang Yang, Fan Ya-Ming, Yi Hong-Mei, Guo Dan-Dan, Wang Feng-Ge, Zhao Jiu-Ran

Acta Agronomica Sinica. 2026, 52(4):  993-1005.  doi:10.3724/SP.J.1006.2026.53084

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The rapid development of high-throughput sequencing, bioinformatics, and genotyping technologies has opened new avenues for the precise identification of crop varieties. In this study, based on 780,000 initially mined multi-allelic variant SNPs from the maize whole genome, a novel set of 40 tri-allelic SNP markers was evaluated and identified using bioinformatics approaches, statistical analysis, targeted sequencing validation, and optimal genetic algorithms. These 40 SNPs are evenly distributed across the 10 maize chromosome pairs, with four markers per chromosome. A comprehensive evaluation and comparison of the 40 SNPs were conducted using genotype data from 200 hybrids and 270 inbred lines. The results showed that: (1) For both hybrids and inbred lines, the PIC values of all loci exceeded the maximum value of 0.375 typical for bi-allelic SNP loci, with average values of 0.470 and 0.480, and average discrimination power (DP) values of 0.68 and 0.57, respectively. (2) Pairwise comparisons using the 40 tri-allelic and 96 bi-allelic SNP markers revealed that the percentage of differential loci among hybrids mainly ranged from 50% to 85% and 50% to 70%, respectively; for inbred lines, the ranges were 35% to 75% and 35% to 60%, respectively. The average percentage of differential loci among varieties increased by 10% for tri-allelic SNPs compared to bi-allelic SNPs. (3) For both hybrids and inbred lines, the average frequencies of the first, second, and third alleles at the 40 tri-allelic loci were 0.58 and 0.57, 0.31, and 0.11 and 0.12, respectively. (4) Clustering analysis showed that the 40 loci effectively classified the 270 inbred lines into 10 heterotic groups, consistent with classifications based on high-density SNP chip data. In summary, this study reports a high-quality, highly discriminative core set of tri-allelic SNP markers, providing a novel marker type for maize variety identification. With their enhanced ability to resolve genetic variation, these markers are expected to complement existing marker systems and contribute to the advancement of molecular identification technologies in crop breeding.

Comparative transcriptome analysis of maize root tips and whole roots in response to iron deficiency

Yang Ya-Li, Xu Ming-Rui, Ma Yue-Fei, Hai Yi-Rui, Liu Kai-Dong, Liu Wan-Mao, Sun Ying

Acta Agronomica Sinica. 2026, 52(4):  1006-1021.  doi:10.3724/SP.J.1006.2026.53063

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Transcriptomic studies investigating root responses to iron (Fe) deficiency have typically used entire underground root systems or mixed whole-root samples, which can dilute the strong transcriptional signals originating from root tips. To uncover the spatially resolved transcriptomic features of Fe deficiency responses in maize primary roots and elucidate the spatial division of labor in Fe uptake and homeostasis, we employed the maize inbred line B73. Seedlings at the three-leaf stage were grown under control (25 μmol L^-1 Fe-EDTA) or Fe-deficient (0 μmol L^-1 Fe-EDTA) conditions. RNA sequencing (RNA-seq) was performed on root tips (0-2 cm) and whole primary roots. An integrated analysis—including differentially expressed genes (DEGs), multi-level gene function enrichment, weighted gene co-expression network analysis (WGCNA), and qRT-PCR validation—was used to systematically compare the molecular mechanisms of Fe deficiency responses between root tips and whole roots. A total of 4206 DEGs (2450 upregulated) were identified in root tips, substantially more than the 325 DEGs (84 upregulated) found in whole roots, highlighting root tips as the key region for Fe sensing and response. Functional enrichment analysis revealed that root tips primarily activated metabolic pathways such as ribosome assembly and the TCA cycle, while whole roots were significantly enriched in processes including lignin biosynthesis and antioxidant defense. Several secondary metabolite biosynthesis pathways—including phenylpropanoid biosynthesis, various plant secondary metabolite biosynthesis, and flavonoid biosynthesis—were enriched in distinct root regions, suggesting diverse roles of secondary metabolites in Fe homeostasis. Genes involved in siderophore biosynthesis were specifically induced in root tips, supporting the synthesis of mugineic acids (MAs), the main phytosiderophores (PS) in grasses, and subsequent Fe chelation. Key transporter genes, such as natural resistance-associated macrophage protein 2 (NRAMP2) and yellow stripe-like protein 12 (YSL12), were predominantly expressed and upregulated in whole roots, facilitating Fe translocation within the plant. Additionally, several bHLH family transcription factors, known regulators of Fe homeostasis, were highly expressed in whole roots, indicating their potential role in coordinating Fe uptake and redistribution. This study delineates the spatially partitioned transcriptional landscape of Fe deficiency responses in primary roots, revealing a strategy in which root tips dominate PS biosynthesis, while whole roots coordinate Fe transport and systemic defense. The identification of spatially specific genes and pathways provides new insights into the molecular mechanisms underlying maize root adaptation to Fe deficiency stress.

Cloning and functional analysis of the dwarf and multi-tiller gene DMT1 in rice

Shi Shao-Jie, Liu Kai, Chen Zi-Yi, Wang Hui-Ying, Li San-He, Zhou Lei, You Ai-Qing

Acta Agronomica Sinica. 2026, 52(4):  1022-1034.  doi:10.3724/SP.J.1006.2026.52038

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Tiller number is a key determinant of rice yield. In this study, we identified a novel natural dwarf and high-tillering mutant, dmt1 (dwarf and multi-tiller 1), which exhibited a tiller number of 155.07±18.53—12.64 times that of the wild type HY67. However, several agronomic traits, including plant height, panicle length, seed setting rate, grain length, and 1000-grain weight, were significantly reduced in dmt1 compared to HY67. Histological analysis suggested that the increased tiller number in dmt1 may result from the premature elongation of tiller buds. Genetic analysis indicated that the dwarf and high-tillering phenotype of dmt1 is controlled by a single recessive locus. Using positional cloning and gene silencing, we successfully isolated the DMT1 gene. Sequence analysis revealed that DMT1 is a novel allele harboring a point mutation in D10/OsCCD8 (LOC_Os01g54270), a key gene in the strigolactone (SL) biosynthesis pathway. The DMT1 protein consists of only the first 279 amino acids of the N-terminal region of OsCCD8. RT-qPCR analysis showed significant differences in the expression levels of genes related to the SL and indole-3-acetic acid (IAA) pathways between HY67 and dmt1. Moreover, exogenous application of IAA significantly induced OsCCD8/DMT1 expression and increased the levels of the SL intermediate products carlactone (CL) and 5-deoxystrigol (5-DS), suggesting that OsCCD8/DMT1 may serve as a key regulatory node in the crosstalk between IAA and SL signaling. This study enriches our understanding of OsCCD8 function and provides valuable genetic material for dissecting the functional domains of the OsCCD8 protein, with important implications for high-yield rice breeding.

Rapid identification of waterlogging tolerance and selection of high waterlogging tolerance germplasm resources of rapeseed (Brassica napus L.)

Tan Wen-Qing, Hui Rong-Kui, Zhang Fan-Li, Qin Lei, Mao Shu-Xiang, Deng Li-Chao, Guo Yi-Ming, Qu Liang, Yan Ming-Li

Acta Agronomica Sinica. 2026, 52(4):  1035-1045.  doi:10.3724/SP.J.1006.2026.55067

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The middle and lower reaches of the Yangtze River constitute the main rapeseed-producing region in China, characterized by a wet and rainy climate that frequently leads to waterlogging. This environmental stress severely affects both the yield and quality of rapeseed. Therefore, developing a rapid and reliable method for identifying waterlogging tolerance and screening waterlogging-tolerant germplasm is of great importance. In this study, we established a fast and effective method to assess waterlogging tolerance during the germination stage by subjecting seeds to 24 hours of waterlogging, followed by a graded evaluation based on growth vigor, survival rate, and the development of cotyledons and root systems after recovery. Using this method, 152 rapeseed germplasms were evaluated, resulting in the identification of 10 highly tolerant, 34 moderately tolerant, 53 generally tolerant, and 55 sensitive germplasms. To validate the reliability of this approach, 32 germplasms previously classified by the rapid method were assessed using the root waterlogging tolerance index during indoor germination, following the “Code of Practice for Identification of Waterlogging Tolerance in Rapeseed”. The results showed that highly tolerant germplasms identified by the rapid method exhibited significantly higher root waterlogging tolerance indices compared to generally tolerant and sensitive ones. Furthermore, 54 germplasms identified by the rapid method were subjected to field validation. A comprehensive field waterlogging tolerance index (D value) was calculated using principal component analysis (PCA) and membership function analysis based on four indices: plant height waterlogging tolerance index, number of primary effective branches waterlogging tolerance index, number of siliques per plant waterlogging tolerance index, and number of seeds per silique waterlogging tolerance index. The results revealed significant variation in field waterlogging tolerance among germplasms, with the D values of highly tolerant lines significantly exceeding those of the generally tolerant and sensitive ones. These findings indicate that the rapid identification method is highly reliable and enables large-scale, efficient screening of waterlogging-tolerant germplasm. Finally, by integrating results from both the rapid identification method and field evaluations, three highly tolerant, ten moderately tolerant, and eight sensitive germplasms were confirmed. These results provide a valuable genetic resource and practical reference for future breeding efforts aimed at improving waterlogging tolerance in rapeseed.

Developing new germplasm of high-quality and early-maturing rice by editing Hd6 via CRISPR/Cas9

Chen Wei, Wei Wan-Juan, Zhao Qi-Bing, Chang Dong-Wei, Yu Ling-Bo, Zhai Peng-Fei, Feng Zhi-Ming, Chen Zong-Xiang, Ren Yang-Tao, Yang Peng, Liu Hai-Lang, Li Zhen-Fu, Yang Yong-Le, Jin Yan-Gang, Zuo Shi-Min

Acta Agronomica Sinica. 2026, 52(4):  1046-1056.  doi:10.3724/SP.J.1006.2026.52033

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Heading date is a key agronomic trait that determines the seasonal and regional adaptability of rice varieties. Hd6 encodes the CK2α subunit, which regulates heading date in rice by phosphorylating florigen regulators. Loss-of-function mutants of Hd6 exhibit earlier heading under long-day conditions. To shorten the growth duration of the elite, tasty, late-season japonica cultivar Nanjing 46 (NJ46) and expand its cultivation range, the Hd6 gene in NJ46 was knocked out using CRISPR/Cas9- mediated gene editing. A target site was designed within the second exon of Hd6, and its specificity was validated by BLAST analysis. The expression vector pCAMBIA1305-Actin:Cas9-sgRNA^Hd6 was constructed and introduced into NJ46 callus via Agrobacterium-mediated transformation. Homozygous mutant lines without exogenous components were screened using PCR. The heading date, major agronomic traits, yield-related traits, and grain quality traits of these lines were evaluated in both central and northern Jiangsu and compared with those of local benchmark cultivars Nanjing 9108 (NJ9108) and Nanjing 518 (NJ518), respectively. In the T₀ generation, 18 transgenic positive plants were obtained. In the T₂ generation, three homozygous mutant lines with different mutation types and free of exogenous sequences were identified: NJ46-hd6ko-1 (TTGG deletion), NJ46-hd6ko-2 (25 bp deletion), and NJ46-hd6ko-3 (G deletion). Their heading dates were 21.1, 24.7, and 21.4 d earlier than that of NJ46, respectively. Among them, NJ46-hd6ko-3 showed similar heading date, theoretical yield, milled rice rate, amylose content, gel consistency, and taste value to NJ9108, but had a shorter plant height and a higher alkali spreading value, indicating superior overall performance and suitability for cultivation in the central Jiangsu region. NJ46-hd6ko-2 showed no significant differences in heading date, theoretical yield, or alkali spreading value compared to NJ518, but demonstrated significantly higher milled rice rate and taste value, along with a shorter plant height, suggesting enhanced overall traits and suitability for the northern Jiangsu region. By precisely editing the Hd6 gene in NJ46, we developed new elite, tasty japonica rice germplasms adapted to the central and northern Jiangsu ecological zones, thereby expanding the cultivation area for high-quality, palatable rice varieties.

Genetic diversity analysis and breeding potential evaluation of innovative sugarcane germplasm based on fluorescent SSR

Tian Chun-Yan, Lu Xin, Wu Cai-Wen, Xu Chao-Hua, Liu Jia-Yong, Bian Xin, Tao Lian-An

Acta Agronomica Sinica. 2026, 52(4):  1057-1072.  doi:10.3724/SP.J.1006.2026.54119

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To clarify the genetic differences between the Yunrui series innovative germplasm and commonly used sugarcane parental resources, and to identify elite new germplasm for sugarcane breeding, two types of materials were analyzed: 61 commonly used sugarcane parents, including both domestic and international varieties (lines), and 54 accessions of Yunrui innovative germplasm. Genetic diversity, genetic relationships, and population structure were evaluated using fluorescent SSR markers. Additionally, agronomic traits of the Yunrui germplasms were assessed in both plant cane and ratoon cane, and comprehensively evaluated using the DTOPSIS method. The results showed that 66 pairs of SSR primers detected 368 and 355 loci in the commonly used parents and Yunrui germplasm, respectively. The gene diversity indices were 0.6746 and 0.6773, and the average polymorphism information content (PIC) values were 0.6179 and 0.6201, indicating high genetic diversity in both groups. UPGMA clustering classified the 115 accessions into five groups, clearly distinguishing the Yunrui germplasm from the commonly used parents. These findings were supported by population structure and principal coordinate analyses, confirming genetic differentiation between the Yunrui germplasm and current parental lines. The DTOPSIS analysis identified 23 Yunrui accessions with superior comprehensive traits. These accessions exhibited promising yield and sugar-related characteristics, suggesting their potential as parents for breeding high-yielding, high-sugar content varieties. This study not only revealed the genetic differentiation between Yunrui innovative germplasm and commonly used parents based on SSR markers, but also demonstrated their breeding potential through comprehensive trait evaluation using the DTOPSIS method. The findings provide valuable parental resources for sugarcane breeding and contribute to broadening the crop’s genetic base.

Phenotypic diversity analysis and comprehensive evaluation of 397 sorghum germplasm resources in Guizhou, China

Xu Jian-Xia, Ding Yan-Qing, Cao Ning, Cheng Bin, Gao Xu, Li Wen-Zhen, Wang Ruo-Ruo, Wang Lei, Zhang Li-Yi

Acta Agronomica Sinica. 2026, 52(4):  1073-1087.  doi:10.3724/SP.J.1006.2026.54116

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To address the challenges of limited varietal diversity and germplasm degradation in Guizhou sorghum production, this study systematically evaluated the phenotypic diversity of 397 sorghum accessions under local ecological conditions, aiming to identify well-adapted germplasm resources and provide a theoretical foundation for genetic improvement and breeding. From 2023 to 2024, 15 phenotypic traits were assessed in Guiyang, Guizhou, using genetic diversity indices, correlation analysis, principal component analysis (PCA), cluster analysis, and broad-sense heritability estimation. Elite accessions were selected based on comprehensive F values and target traits. The accessions exhibited rich phenotypic variation, with Shannon-Wiener indices ranging from 0.919 to 2.052. Panicle shape showed the lowest diversity, while plant height displayed the highest. Plant height and growth period had the highest broad-sense heritability, indicating strong genetic control. Domestic accessions outperformed foreign ones in stem diameter, panicle length, and grain length, whereas foreign accessions were superior in dwarfism and 1000-grain weight. Correlation analysis revealed that panicle type and panicle shape were extremely significantly and positively correlated, and both were highly positively correlated with panicle length and plant height, but were extremely significantly and negatively correlated with the number of cob nodes, 1000-grain weight, and grain width. Plant height was extremely significantly and positively correlated with growth period, stem diameter, internode number, and panicle length. In addition, 1000-grain weight was extremely significantly and positively correlated with grain width, and glume color with grain color. PCA extracted four principal components (eigenvalues > 1), accounting for 66.43% of the total variance, corresponding to panicle morphology and plant height, grain yield, growth characteristics, and grain appearance quality. Cluster analysis grouped the accessions into five categories. Group IV, characterized by dwarf stature, high 1000-grain weight, and compact architecture, was suitable for dense planting and high yield; Group V, with tall plants and broom-shaped panicles, was suitable for industrial applications. Twenty elite accessions—including Erluhuangke, Hongmaonuo 2, Tiangaoliang (Xuanwei), B martin, and GL002—were selected based on comprehensive evaluation. In conclusion, the 397 sorghum accessions exhibited substantial phenotypic diversity under Guizhou conditions. Plant height and growth period, showing high genetic stability, represent key target traits for genetic improvement. The selected elite germplasms possess complementary trait profiles and offer valuable parental resources for diverse breeding objectives.

Establishment and optimization of near-infrared spectroscopy models for quality traits of purple-fleshed sweet potato

Jiang Jia-Hui, Jiang Bing-Zhi, Liu Guan-Ming, Wang Zhang-Ying, Tang Chao-Chen

Acta Agronomica Sinica. 2026, 52(4):  1088-1102.  doi:10.3724/SP.J.1006.2026.54108

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The lack of precise and efficient methods for evaluating the quality of purple-fleshed sweet potato has become a major bottleneck in accurate germplasm identification and genetic improvement. To address this challenge, this study employed near-infrared spectroscopy (NIRS) to construct and optimize high-throughput predictive models for key quality traits of purple-fleshed sweet potato, including total starch, crude protein, reducing sugar, total flavonoid content, total phenolic content and total anthocyanin content. A total of 150 representative samples were selected, and six high-performance predictive models were successfully developed and optimized using a dual optimization strategy combined with machine learning algorithms. The models achieved high accuracy, with coefficients of determination (R²_C) for calibration ranging from 0.936 to 0.992, cross-validation (R²_CV) from 0.918 to 0.987, and external validation (R²_V) from 0.903 to 0.987. The ratio of prediction deviation (RPD) ranged from 6.55 to 19.80, and the range error ratio (RER) ranged from 21.9 to 63.4, indicating strong model stability and prediction capability. The predictive models developed in this study offer an efficient and practical approach for the high-throughput analysis of purple-fleshed sweet potato quality. They enable quantitative evaluation of nutritional components and facilitate the screening of superior germplasm, thereby providing important technical support for quality improvement and the sustainable development of the purple-fleshed sweet potato industry.

Molecular mechanism of CsERF9-mediated regulation of anthracnose resistance in tea plant

Yang Ying, Hao Yu-Wan, Zhang Xue-Ning, Fang Jia-Lu, Ma Yue-Hua, Yang Wei-Long, Sun Wen-Qing, Wang Xin-Chao, Wang Yu-Chun, Huang Jian-Yan

Acta Agronomica Sinica. 2026, 52(4):  1103-1115.  doi:10.3724/SP.J.1006.2026.54106

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Tea plant (Camellia sinensis) is a globally important economic crop. Anthracnose, a major fungal disease caused by Colletotrichum camelliae, seriously threatens tea plant growth and leaf quality. Members of the ethylene response factor (ERF) family are key regulators in plant disease resistance signaling pathways. To identify critical genes involved in tea plant defense, this study screened differentially expressed genes based on previously obtained transcriptome data from tea plants inoculated with C. camelliae strain LS_19. From these, the candidate gene CsERF9 was selected for systematic investigation. Subcellular localization analysis confirmed that CsERF9 is localized in the nucleus, consistent with its predicted function as a transcription factor. Promoter cis-element analysis revealed that the CsERF9 promoter region is enriched with various defense- and hormone-response related elements, suggesting its potential involvement in pathogen-induced hormonal signaling. RT-qPCR results showed that CsERF9 expression was significantly induced upon C. camelliae infection and remained upregulated during later stages (24 h post-inoculation and beyond). Functional validation demonstrated that transient overexpression of CsERF9 in tea leaves significantly reduced resistance to anthracnose. Compared with the empty vector control, lesion areas in CsERF9-overexpressing leaves increased by 170.6%, 48.9%, and 40.7% at 24, 48, and 72 h post-inoculation, respectively, indicating that CsERF9 acts as a negative regulator of tea plant resistance to anthracnose. Further analysis revealed that CsERF9 overexpression significantly suppressed the expression of the salicylic acid (SA) pathway marker gene CsPR1, while upregulating the jasmonic acid/ethylene (JA/ET) pathway marker gene CsPR3. These findings suggest that CsERF9 may negatively regulate the tea plant’s immune response to C. camelliae by suppressing SA-mediated defenses and activating JA/ET signaling, thereby disrupting the balance between distinct disease-resistance pathways. This study provides novel insights into the molecular network of tea plant resistance to anthracnose and identifies CsERF9 as a potential candidate gene target for breeding disease-resistant tea cultivars.

Genome-wide identification of the Argonaute gene family and its induction by late blight in potato (Solanum tuberosum L.)

Tian Li-Tao, Ding Ning, Wang Shu-Lin, Qi En-Fang, Zhang Rong, Wang Rui-Rui, Ma Li-Wen, Li Jian-Wu, Yang Jiang-Wei

Acta Agronomica Sinica. 2026, 52(4):  1116-1126.  doi:10.3724/SP.J.1006.2026.54114

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Argonaute (AGO) proteins are core components of the RNA-induced silencing complex (RISC) and play a crucial role in small RNA (sRNA)-mediated gene silencing. In plants, AGO proteins regulate key biological processes such as development, stress responses, genome architecture, and pathogen defense. However, the AGO gene family in potato (Solanum tuberosum L.) has not yet been characterized. In this study, we identified members of the StAGO gene family through bioinformatics approaches and analyzed their expression patterns in various tissues and in leaves infected by Phytophthora infestans (Mont.) de Bary using real-time quantitative PCR (RT-qPCR). The expression of StAGO1A and StAGO2A under pathogen stress was further validated using a transient expression assay in Arabidopsis protoplasts. A total of 14 StAGO genes were identified in the doubled haploid potato genome, distributed across seven chromosomes. Phylogenetic analysis grouped them into three subfamilies: StAGO1A, StAGO1B, StAGO5, StAGO10, StAGO10A; StAGO2A, StAGO2B, StAGO3, StAGO7; and StAGO4A, StAGO4B, StAGO4, StAGO6, StAGO8. Collinearity analysis revealed two segmental duplication events within the family (StAGO1A and StAGO1B, StAGO4A and StAGO4B). Tissue-specific expression analysis by RT-qPCR showed that StAGO10 was highly expressed in leaves, StAGO1B showed elevated expression in stems, and StAGO3, StAGO5, and StAGO7 exhibited relatively high expression in mini tubers. Moreover, expression profiling following infection with the late blight pathogen revealed significant upregulation of StAGO1A, StAGO2A, StAGO3, StAGO5, StAGO6, and StAGO10. Transient expression assays in Arabidopsis protoplasts further confirmed that P. infestans infection induces the expression of StAGO1A and StAGO2A. In conclusion, this study provides a theoretical foundation for future functional analyses of the StAGO gene family and their roles in potato defense against late blight.

Genome-wide identification of the AP2 subfamily in broomcorn millet and functional characterization of PmAP2-1 and PmAP2-9 in salt tolerance

Song Yu-Zhen, Bheel Chander Kumar, Wang Yue, Zhang Ying-Xing, Guo Juan, Khound Rituraj, Santra Dipak Kumar, Cao Xiao-Ning, Wang Rui-Yun

Acta Agronomica Sinica. 2026, 52(4):  1127-1139.  doi:10.3724/SP.J.1006.2026.54118

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Broomcorn millet is an ancient cereal crop that originated in China and plays a foundational role in the development of Chinese agricultural civilization. The AP2 subfamily has been shown to regulate plant growth, development, and responses to abiotic stresses; however, the number and its specific functions in broomcorn millet remain unclear. In this study, we performed a genome-wide identification of members of the AP2 subfamily in broomcorn millet using bioinformatics approaches based on its genome sequence. Analyses included gene structures and expression patterns under salt stress. A total of 20 PmAP2 subfamily members (PmAP2-1 to PmAP2-20) were identified at the genome-wide level, distributed across 15 chromosomes. Phylogenetic analys is clustered all PmAP2 encoded proteins into three subgroups: euANT, basalANT, and euAP2. Promoter cis-acting element analysis revealed that genes of the PmAP2 subfamily are involved in multiple biological processes, including plant hormone and abiotic stress, growth and development, and light responsive. Interspecies synteny analysis identified 3 and 27 syntenic gene pairs between broomcorn millet and Arabidopsis thaliana and Oryza sativa, respectively. Expression profiling indicated that PmAP2 genes exhibit both cultivar and tissue specificity, and the expression of all 20 members was induced by salt stress. PmAP2-1 and PmAP2-9, two salt stress-induced upregulated genes from broomcorn millet, were introduced into Arabidopsis thaliana via genetic transformation, and stably heritable transgenic lines were obtained. Root growth in transgenic Arabidopsis thaliana was affected by salt stress, with root length decreasing as the NaCl concentration increased. Under severe salt stress of 75 mmol L^-1 and 100 mmol L^-1 NaCl, the root lengths of transgenic plants showed significant differences compared with the wild type. These findings suggest that PmAP2-1 and PmAP2-9 may serve as potential target genes for the genetic improvement of salt tolerance in other staple crops.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Spatiotemporal evolution of rapeseed phenological periods in the Middle and Lower Reaches of the Yangtze River from 1981 to 2024

Zhang Quan-Jun, Wu Dong-Li, Liu Cong, Zhu Yong-Chao, Yang Da-Sheng, Kong Xiang-Sheng

Acta Agronomica Sinica. 2026, 52(4):  1140-1152.  doi:10.3724/SP.J.1006.2026.55062

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To elucidate the response mechanisms of rapeseed phenological stages to geographical environments and climate change in the Middle and Lower Reaches of the Yangtze River Plain, this study systematically analyzed the spatiotemporal patterns of key phenological stages and their durations using observational data from 50 meteorological stations spanning 1981 to 2024. Methods employed included kernel density estimation, linear trend analysis, and correlation analysis. The results revealed that: (1) Spatially, the relationship between rapeseed phenology and geographical factors exhibited a distinct stage-dependent shift. During the vegetative growth stage (sowing to five-leaf), phenological timing advanced with increasing latitude (“high-latitude & early-sowing”), showing significant negative correlations with latitude (r = -0.200 to -0.285), primarily reflecting agronomic strategies to avoid winter frost. In contrast, during the reproductive growth stage (flowering to maturity), the pattern reversed to “high-latitude & late-flowering,” with strong positive correlations with latitude (r = 0.665 to 0.731), suggesting that photoperiod and accumulated heat became dominant controlling factors. (2) Temporally, a coordinated pattern of “delayed early stages but advanced later stages” and “shortened initial phases but prolonged subsequent phases” was observed. From 1981 to 2024, over half of the sites (50%-58%) exhibited delays in vegetative stages, while reproductive stages tended to advance (64%-88%), with significantly earlier flowering observed at 88% of the stations. Phase duration shortened from sowing to flowering at 56%-68% of the sites, but lengthened after flowering—especially from green-ripening to maturity—at 78% of the sites, resulting in an overall shortened growth cycle at 64% of locations. (3) This phenological evolution is closely linked to the seasonal asymmetry of climate change in the region, characterized by slower autumn warming and more rapid spring warming. These findings offer new insights into the geographical adaptation mechanisms of rapeseed phenology and provide valuable guidance for developing region-specific adaptive strategies for rapeseed production under global climate change.

Study on breeding and cultivation strategies for winter rapeseed to cope with climate change in the lower reaches of the Yangtze River

Yang Rui, Chen Jing-Dong, Huang Ying, Zhang Xue-Kun, Zhou Deng-Wen, Liu Qing-Yun, Xu Jin-Song, Xie Ling-Li, Xu Ben-Bo

Acta Agronomica Sinica. 2026, 52(4):  1153-1165.  doi:10.3724/SP.J.1006.2026.55056

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Climate change has a significant impact on rapeseed production, making it essential to clarify breeding and management strategies under evolving climatic conditions to ensure production stability. To systematically investigate the relationships between meteorological factors and yield, oil yield, and resistance-related traits, multi-year and multi-location national trial data from major production areas in the lower reaches of the Yangtze River during 2009-2023 were analyzed using a mixed linear model (MLM), linear regression, and canonical correlation analysis. Results showed a significant increase in mean temperature during the rapeseed growing season in this region, accompanied by greater temperature fluctuations and increased precipitation variability. Overall, the rise in mean temperature was beneficial for improving yield and oil production; however, extreme weather events substantially weakened this positive effect, and low temperatures in November had a particularly negative impact on yield. Canonical correlation analysis revealed two dominant meteorology-trait coupling patterns: Type 1 (humid late autumn-moderately cool early spring-moderately warm late spring), which supported safe overwintering, strong regrowth, and effective disease control, thereby significantly boosting yield but potentially reducing oil content; and Type 2 (cold spring), which was associated with suppressed yield and structural traits, as well as increased disease risk. It is recommended to enhance monitoring and early warning systems for extreme weather, especially low temperatures in November, and to adopt targeted management strategies. Under different climatic scenarios, differentiated field practices and a “dual-target” breeding strategy should be implemented: in warm and moist favorable years, optimize planting density and nutrient management to enhance oil content and thousand-seed weight; in cold spring years, apply timely control measures for Sclerotinia sclerotiorum rot and reinforce nutrient supply during the flowering to maturity stages. Breeding efforts should focus simultaneously on developing high-yield, disease-resistant genotypes and high-oil, high-thousand-seed-weight genotypes to enhance adaptability under complex climate conditions. A multidimensional meteorology-trait-yield early warning system should be established, integrating historical climate patterns with future projections to enable dynamic optimization of cultivar selection and field management.

Key mechanisms underlying the enhancement of sweet maize yield through partial substitution of chemical fertilizers with organic manure in arid irrigation districts

Cai Hong-Wei, Yu Ai-Zhong, Jiang Ke-Qiang, Wang Peng-Fei, Wang Yu-Long, Huo Jian-Zhe, Pang Xiao-Neng, Yin Bo, Shang Yong-Pan

Acta Agronomica Sinica. 2026, 52(4):  1166-1180.  doi:10.3724/SP.J.1006.2026.53073

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This study investigated the effects of partially replacing chemical fertilizers with organic fertilizers on sweet maize yield in the oasis irrigation area and explores the underlying mechanisms, aiming to provide a theoretical basis for optimizing high-yield cultivation practices in this region. Field trials were conducted in the Northwest Oasis Irrigation District from 2023 to 2024, with five levels of organic fertilizer substitution: 0% (CK), 10% (M1), 20% (M2), 30% (M3), and 40% (M4). The study examined the effects of different substitution ratios on soil nutrients, photosynthetic characteristics, and sweet maize yield. Compared with CK, both M1 and M2 treatments enhanced sweet maize growth and soil nutrient accumulation, with M2 showing superior results. the M2 treatment increased dry matter accumulation (DMA), fresh ear yield (EY), and fresh grain yield (GY) by 11.17%, 4.51%, and 6.31%, respectively. Soil total nitrogen (TN), available phosphorus (AP), and available potassium (AK) increased by 28.23%, 7.07%, and 3.93%, respectively. Net photosynthetic rate (P_n), stomatal conductance (G_s), and transpiration rate (T_r) increased by 1.36%, 16.14%, and 34.34%, respectively, and all differences were statistically significant. Although M3 and M4 treatments increased stomatal conductance and transpiration rate, they reduced crop yield and soil nutrient content. Correlation analysis indicated that TN, soil organic matter (SOM), root biomass (RB), SPAD, leaf area index (LAI), DMA, AK, T_r, AP, and P_n are key factors influencing EY and GY. To clarify the regulatory pathways among these variables, partial least squares structural equation modeling (PLS-SEM) revealed that soil nutrients influence RB, which directly affects LAI and photosynthetic parameters. LAI and photosynthetic parameters, in turn, directly influence DMA, ultimately affecting EY and GY. In summary, replacing 20% of chemical fertilizer with organic fertilizer enhances yield by improving soil fertility and photosynthetic efficiency in sweet maize. This approach offers a rational strategy for organic-inorganic fertilizer management in oasis irrigation systems.

Study on the effects of long-term no-tillage straw mulching on wheat yield improvement in dryland areas based on the APSIM model

Qiao Yu-Xin, Li Cheng-Yue, Kang Xiao-Yu, Zhang Xin-Qi, Jia Shao-Hui, Liu Qian, Cao Ya-Li, Shi Xin-Rui, Hao Xing-Yu, Li Ping

Acta Agronomica Sinica. 2026, 52(4):  1181-1192.  doi:10.3724/SP.J.1006.2026.51067

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Traditional rotary tillage and plowing practices often lead to water and nutrient loss in dryland farming regions. Investigating the effects of minimum and no-tillage practices on soil moisture and wheat yield in dryland systems is therefore crucial for water conservation and yield stability. This study conducted two growing seasons of dryland wheat experiments in Yaodu district, Linfen city, Shanxi province, using two tillage methods: no-tillage with straw mulching (NT) and rotary tillage with straw incorporation (RT). The wheat variety used was “Jinmai 102”. The APSIM-Wheat model was calibrated and validated using observed data on soil water storage, biomass, and yield at various growth stages. The validated model was then employed to simulate the growth, soil moisture dynamics, and yield of winter wheat over 39 years of historical meteorological data in Yaodu. The impacts of different annual precipitation patterns and tillage methods on wheat yield, soil water storage, and water use efficiency (WUE) were analyzed. Compared with rotary tillage, no-tillage with straw mulching increased wheat yield by 31.1%, 21.0%, and 28.5% in normal, wet, and dry years, respectively. During the fallow period, soil water retention improved by 26.6%, 35.9%, and 37.5%, and WUE increased by 29.0%, 10.0%, and 9.9%, respectively. However, there was no significant difference in evapotranspiration during the wheat growing period between the two tillage methods. Under treatment NT, wheat yield was significantly positively correlated with both fallow-period and annual precipitation. Moreover, under NT, yield was significantly correlated with soil water retention during the fallow period, whereas no such correlation was observed under RT. Overall, no-tillage with straw mulching enhances dryland wheat yield on the Loess Plateau primarily by improving soil water retention during the fallow period, making it an effective tillage strategy for yield stability in this region.

Effects of nitrogen application at different densities on carbon and nitrogen accumulation and translocation characteristics in forage maize in semi-arid regions

Ma Hai-Hui, Zhang Guo-Ping, Yang Si-Cun, Wang Hong-Li

Acta Agronomica Sinica. 2026, 52(4):  1193-1207.  doi:10.3724/SP.J.1006.2026.53064

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To provide a theoretical basis for high-yield and high-quality cultivation of silage maize in semi-arid regions, this study investigated the effects of nitrogen application on carbon and nitrogen accumulation, translocation, and crude protein synthesis in silage maize under different planting densities. Using ‘Longqingzhu 1’ as the experimental material, two planting densities (60,000 and 75,000 plants hm^-2) and three nitrogen application regimes (all nitrogen as basal fertilizer, 40% and 60% of nitrogen applied as topdressing at the bell stage) were examined. Measurements included dry matter, non-structural carbohydrate (NSC), and nitrogen accumulation and translocation before and after flowering, as well as their contribution to total plant biomass. Correlations between these physiological parameters and forage yield, crude protein content, and crude protein yield were also analyzed. Compared with CK1 (60,000 plants hm^-2 with all nitrogen applied basally), treatments T1 and T2 (same density with 40% and 60% nitrogen topdressing, respectively) showed significantly reduced dry matter and NSC translocation and contribution rates at the pre-flowering stage, but significantly increased post-flowering dry matter accumulation by 46.29% and 22.63%, and NSC accumulation by 29.53% and 17.54%, respectively. Compared with CK2 (75,000 plants hm^-2 with all nitrogen applied basally), T3 and T4 (same density with 40% and 60% nitrogen topdressing, respectively) also showed reduced translocation and contribution rates at the pre-flowering stage, while post-flowering dry matter increased by 5.88% and 5.90%, and NSC accumulation increased by 19.53% and 65.57%, respectively. Nitrogen topdressing significantly increased nitrogen translocation and translocation rate at the pre-flowering stage, as well as nitrogen accumulation at the post-flowering stage. Compared with CK1, T1 showed increases of 64.48%, 7.77%, and 74.86%, while T2 increased by 43.21%, 7.52%, and 32.27%, respectively. Compared with CK2, T3 increased by 12.51%, 8.92%, and 74.94%, and T4 by 47.37%, 8.75%, and 73.41%, respectively. Forage yield was significantly positively correlated with post-flowering dry matter accumulation (R² = 0.1547^*) and nitrogen accumulation (R² = 0.1582^*). Crude protein content was positively correlated with pre-flowering nitrogen translocation (R² = 0.1263^*), post-flowering nitrogen accumulation (R² = 0.1764^**), and NSC accumulation (R² = 0.2155^**). The crude protein yield of the whole plant was significantly positively correlated with post-flowering dry matter (R² = 0.1723^*) and nitrogen accumulation (R² = 0.1682^*). These results indicate that nitrogen topdressing significantly promotes crude protein synthesis in silage maize by enhancing nitrogen translocation at the pre-flowering stage and carbon and nitrogen accumulation at the post-flowering stage. The crude protein content of T1 and T2 was 9.42% and 8.40%, which was 62.18% and 44.80% higher than that of CK1, respectively. The crude protein content of T3 and T4 was 7.06% and 8.12%, 39.25% and 60.15% higher than that of CK2, respectively. Therefore, T1 and T4 are recommended for improving silage maize quality in semi-arid regions.

Effects of green manure combined with chemical nitrogen fertilizer on dry matter accumulation and yield formation of wheat in arid irrigation areas of northwestern China

Hou Si-Yu, Wang Guo-Cui, Wei Jin-Gui, Xie Wei-Xin, Yin Wen, Fan Zhi-Long, Chai Qiang, Hu Fa-Long

Acta Agronomica Sinica. 2026, 52(4):  1208-1219.  doi:10.3724/SP.J.1006.2026.51083

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To address the lack of suitable green manure application techniques for efficient wheat production and the underutilized yield potential in the arid irrigated regions of Northwest China, this study examined the effects of green manure combined with chemical nitrogen fertilizer on wheat dry matter accumulation, translocation, distribution, and yield formation. The objective was to identify optimal green manure management strategies for high-yield wheat cultivation. From 2022 to 2024, a two-factor randomized block design was implemented with wheat as the experimental crop. Treatments included two nitrogen levels: no chemical nitrogen fertilizer (N0) and 180 kg hm^-2 of chemical nitrogen fertilizer (N1), and four green manure treatments: fallow after wheat harvest (G0) and incorporation of green manure at 15,000 kg hm^-2 (G1), 30,000 kg hm^-2 (G2), and 45,000 kg hm^-2 (G3). Results showed that both green manure and chemical nitrogen fertilizer significantly improved wheat yield and harvest index, with green manure enhancing the yield-increasing effect of nitrogen fertilizer. Compared to N0, N1 increased grain yield, biological yield, and harvest index by 23.0%, 11.8%, and 10.4%, respectively. Compared to G0, G1, G2, and G3 increased grain yield by 22.2%, 32.5%, and 35.5%; biological yield by 14.4%, 18.5%, and 20.0%; and harvest index by 7.2%, 12.1%, and 13.4%, respectively. Furthermore, N1G1, N1G2, and N1G3 increased grain yield by 15.4%, 27.0%, and 24.0%; biological yield by 8.8%, 11.6%, and 11.2%; and harvest index by 6.1%, 13.8%, and 11.4%, respectively, compared with N1G0, with the highest yield observed in N1G2. Both green manure and nitrogen fertilizer enhanced the rate of dry matter accumulation, pre-anthesis translocation, and post-anthesis accumulation, as well as dry matter distribution to grains at maturity. Green manure reinforced the effects of nitrogen fertilizer on dry matter dynamics, with the most notable improvements observed at the 30,000 kg hm^-2 incorporation rate. Compared to N1G0, N1G2 increased dry matter accumulation rates during the seedling to jointing, jointing to flowering, and flowering to maturity stages by 7.9%, 11.1%, and 8.0%, respectively. The maximum and average dry matter growth rates throughout the growing season increased by 10.4% and 11.5%, respectively. Post-anthesis accumulation and its contribution to total dry matter increased by 40.0% and 10.2%, while grain dry matter at maturity and its proportion increased by 27.0% and 14.0%, respectively. The application of green manure at 30,000 kg hm^-2 combined with 180 kg hm^-2 of chemical nitrogen fertilizer effectively promoted dry matter accumulation and translocation, making it a promising practice for achieving high wheat yields in the irrigated areas of Northwest China.

Study on the relationship between physiological characteristics of superior and inferior grains with yield in different oat genotypes

Cui Xue-Mei, Liu Yan-Di, Liu Jing-Hui, Mi Jun-Zhen, Wu Jun-Ying, Zhao Bao-Ping

Acta Agronomica Sinica. 2026, 52(4):  1220-1235.  doi:10.3724/SP.J.1006.2026.51079

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To investigate the physiological characteristics of superior and inferior oat grains and their impact on yield, field experiments were conducted in 2021 and 2022 at the Modern Agricultural Science and Technology Park of Inner Mongolia Agricultural University, located in Tumd Right Banner, Baotou City, Inner Mongolia Autonomous Region. Nine oat varieties were used as experimental materials to determine the sucrose metabolism, starch content and related enzyme activities during the grain-filling period and the grain yield at maturity. Correlation and path analyses were performed to elucidate the relationships between physiological traits of superior and inferior grains and overall yield. The results showed that, based on grain yield at maturity, Bayou 1, Bayou 9, Bayou 18, and Caoyou 1 were classified as high-yielding varieties (2582.67-3341.29 kg hm^-2), whereas Huabei 2, Baiyan 5, Baiyan 2, Dingyou 8, and Pin 5 were classified as low-yielding varieties (1894.05-2397.45 kg hm^-2). Compared to the low-yielding varieties, the grain yield of the high-yielding varieties increased significantly by 5.39% to 76.41%. Notably, although the sucrose content in superior grains was lower than in inferior grains, sucrose synthase (SUS) activity was higher. Additionally, starch content, starch synthase (SSS), and ADP-glucose pyrophosphorylase (AGPase) activities were all higher in superior grains than in inferior ones, indicating a higher efficiency of sucrose cleavage and conversion into starch in superior grains. Grain yield showed positive correlations with starch content, SUS, SSS, and AGPase activities in the top, middle, and bottom portions of the panicle, and negative correlations with sucrose content. Moreover, yield was negatively correlated with sucrose phosphate synthase (SPS) activity specifically in the top part of the panicle. Path analysis revealed that SSS activity in superior grains had the greatest positive effect on yield, while SUS activity in inferior grains also contributed significantly. In conclusion, enhancing starch synthesis capacity in superior grains and improving sucrose metabolism in inferior grains can effectively increase oat yield.

Effects of long-term tillage practices on grain-filling and yield formation in rain-fed wheat

Shang Yun-Qiu, Zhao Zhu, Chen Huan, Ding Yong-Gang, Qiao Yu-Qiang, Li Wei, Zhang Xiang-Qian, Cao Cheng-Fu, Du Shi-Zhou

Acta Agronomica Sinica. 2026, 52(4):  1236-1250.  doi:10.3724/SP.J.1006.2026.51074

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Seasonal drought remains a major constraint to yield improvement in the rain-fed wheat region of Huang-Huai-Hai. This study explores the physiological and ecological mechanisms by which tillage practices enhance drought resistance and conserve soil moisture to stabilize wheat production, aiming to provide a theoretical foundation for optimizing drought-resilient regional farming systems. Based on a 14-year long-term field experiment using the wheat cultivar Jimai 22, three tillage systems were compared: perennial deep tillage with straw incorporation (DT), perennial rotary tillage (RT), and perennial minimum/no tillage (NT). Field measurements during the 2018-2020 growing seasons included assessments of soil water consumption, assimilate translocation and assimilation dynamics, grain filling characteristics, and yield components. While total soil water consumption within the 0-60 cm soil layer did not differ significantly among DT, RT, and NT treatments, DT significantly reduced water consumption during the sowing-to-jointing period by 19.64%-29.67% (2018-2019) and 5.12%-10.97% (2019-2020) compared with RT and NT, and conversely increased water consumption during the jointing-to-maturity period by 17.16%-45.38% and 7.20%-12.74% in the respective years. No significant differences in post-anthesis dry matter assimilation were observed between DT and RT, but both were significantly higher than NT. Additionally, DT enhanced the contribution of post-anthesis assimilates to grain by 0.50-20.07 percentage points (2018-2019) and 4.32-16.29 percentage points (2019-2020) compared to RT and NT, respectively. Logistic equation fitting indicated that DT achieved higher maximum and mean grain filling rates and longer grain filling durations than both RT and NT. Correlation analysis further revealed that increased soil water consumption during the anthesis-to-maturity period was the primary driver for enhanced post-anthesis assimilate accumulation, improved grain filling parameters, and increased grain yield. Ultimately, DT resulted in a 15.67% yield increase over NT in 2018-2019, and yield improvements of 5.34% and 8.61% over NT and RT, respectively, in 2019-2020. Therefore, compared to rotary tillage and minimum/no-till systems, deep tillage with straw incorporation emerges as the most effective strategy for stabilizing and enhancing rain-fed wheat yields. This is achieved through a water management advantage characterized by early-stage water conservation and late-stage water supply compensation, which collectively enhance post-anthesis assimilate accumulation and translocation, significantly increase grain filling rates, prolong the effective grain filling period, and synergistically optimize yield components including spike number, kernels per spike, and thousand-kernel weight.

Effects of CO₂ and NaCl on stomatal traits, photosynthetic performance, and antioxidant systems in soybean

Li Kun, Ji Ya-Teng, Tian Yin-Shuai, Hu Min-Hang, Liu Liang, Li Fei, Li Guo-Qiang, Hao Li-Hua, Zheng Yun-Pu

Acta Agronomica Sinica. 2026, 52(4):  1251-1267.  doi:10.3724/SP.J.1006.2026.55057

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To gain a deeper understanding of the response mechanisms of farmland ecosystems under NaCl stress in the context of future elevated atmospheric CO₂ concentrations, this study employed environmental growth chambers with precisely controlled CO₂ levels to investigate the effects of elevated CO₂ on stomatal morphology and distribution, leaf gas exchange parameters, and the antioxidant enzyme system in soybeans under NaCl stress. The results showed that under ambient CO₂ conditions, NaCl stress reduced stomatal density, length, width, perimeter, and area on the adaxial surface. In contrast, elevated CO₂ increased stomatal density and promoted a more regular stomatal distribution, thereby mitigating the negative effects of NaCl on leaf gas exchange efficiency. Moreover, NaCl stress decreased the net photosynthetic rate (P_n), while elevated CO₂ significantly improved leaf water use efficiency under NaCl stress (S₀, S₅₀, S₁₀₀, and S₁₅₀) by 188%, 243%, 97%, and 85%, respectively, compared to ambient CO₂, indicating that elevated CO₂ can effectively alleviate NaCl-induced physiological stress in soybeans. Elevated CO₂ also enhanced peroxidase and superoxide dismutase activities and increased proline content, while reducing malondialdehyde levels under severe NaCl stress. Furthermore, under NaCl stress, elevated CO₂ downregulated the expression of GmCLC-d1, GmCLC-d2, and GmNHX1, and upregulated GmNcl1. These findings demonstrate that elevated atmospheric CO₂ can alleviate the physiological damage caused by NaCl stress in soybeans by optimizing stomatal traits, enhancing photochemical and biochemical processes, boosting antioxidant defenses, and regulating salt-tolerance gene expression. This study provides a theoretical basis for understanding the physiological and molecular responses of soybeans to elevated CO₂ and NaCl stress under future climate change scenarios.

RESEARCH NOTES

Cloning of the IbOPR2 gene promoter and identification of regulatory factors in sweetpotato

Wang Yi-Han, Li Fu-Chang, Liu Yi, Zhu Guo-Peng

Acta Agronomica Sinica. 2026, 52(4):  1268-1276.  doi:10.3724/SP.J.1006.2026.54079

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Jasmonic acids (JAs), as endogenous plant hormones, play a crucial role in the plant response to salt stress. 12-oxophytodienoate reductase (OPR), a key enzyme in JA biosynthesis, remains poorly understood in terms of its expression regulation. To identify transcription factors involved in regulating IbOPR2 expression, this study used the salt-tolerant sweetpotato cultivar ‘Haida 7791’ to clone the promoter sequence of the IbOPR2 gene. Bioinformatics analysis revealed various cis-acting elements, and transcriptional activation assays confirmed promoter activity. Yeast one-hybrid (Y1H) screening was conducted to identify transcription factors interacting with the promoter, and point-to-point Y1H assays were used to validate specific binding. A 1964 bp promoter sequence upstream of IbOPR2 was successfully cloned, containing recognition motifs such as MYBHv1, MYB, and WRKY, along with stress-responsive elements (MYB, MYC) and MeJA-responsive elements, indicating strong transcriptional activation potential. Five candidate transcription factors—PHL7, ZFP16, SKIP11, TGA2, and ERF2—were identified using MYC and MeJA response elements as bait in Y1H assays. Follow-up point-to-point verification confirmed that IbPHL7, IbZFP16, and IbSKIP11 specifically bind to the IbOPR2 promoter. Dual-luciferase reporter assays further demonstrated that these three transcription factors could activate the IbOPR2 promoter. Moreover, qRT-PCR analysis showed that the expression of IbPHL7, IbZFP16, and IbSKIP11 is responsive to salt stress in sweetpotato. Taken together, these results suggest that these transcription factors may function as upstream regulators of IbOPR2, modulating its expression under salt stress conditions. This study represents the first identification of transcriptional regulators of sweetpotato IbOPR2, providing a foundation for further investigation into its regulatory mechanisms in response to salt stress.